where \(P\)  and \(\mathcal {E}\)  denote the pressure and energy density, respectively, and \(\mathcal {E}_{\rm tr}\)  is the transition energy density. For the construction of the EoSs, we adopted the following: (a) in region \({\cal E} \le {\cal E}_{\rm c-edge}\) , we used the equation of Feynman et al. [1]} and also of Baym et al. [2]} for the crust and low densities of neutron star, (b) in the intermediate region, \({\cal E}_{\rm c-edge} \le {\cal E} \le {\cal E}_{\rm tr}\) , we employed a specific EoS based on the MDI model and data from Akmal et al. [3]}, and (c) for \({\cal E}_{\rm tr}\ge \mathcal {E}\)  region, the EoS is maximally stiff with the speed of sound, defined as \(v_s=c\sqrt{\left(\partial P / \partial {\cal E}\right)}_{\rm S}\)  (where \(S\)  is the entropy) fixed in the present work in the range \([c/\sqrt{3},c]\) . The implementation of speed of sound values between the limited ones will lead to results well constrained by the two mentioned limits. Although the energy densities below the \({\cal E}_{\rm c-edge}\)  have negligible effects on the maximum mass configuration, we used them in calculations for the accurate estimation of the tidal deformability.
The cases which took effect in this study can be divided into two categories based on the fiducial baryon transition density, \(n_{\rm tr} = p n_{\rm s}\) , and the speed of sound as: (a) the ones where \(p\)  takes the values \([1.5,2,3,4,5]\) , while the speed of sound is parametrized in the two limiting cases, \((v_{s}/c)^{2}=1/3\)  and \((v_{s}/c)^{2}=1\)  and (b) the ones where \(p\)  takes the values \([1.5,2]\) , while the speed of sound is parametrized in the range \((v_{s}/c)^{2}=[1/3,1]\) . The predicted EoSs are functional of \(n_{\rm tr}\)  and \((v_s/c)\)  and implemented to study the possibly existence of a neutron star with \(\sim 2.6~M_{\odot }\) , either non-rotating or a rotating one.
